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Date: Tue, 10 Jan 2012 00:58:39 +0100
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Subject: Re: Object-Oriented style question
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Date: 2012-01-10T00:58:35+01:00
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On 1/9/12 9:55 AM, Maciej Sobczak wrote:

> But I think that in one particular case you might want to distinguish
> between these profiles - access value is a "name" of the object, not
> the object itself, and therefore can be used for more involved lookup.
> Like in a dictionary, where access values are lightweight keys.
> Then, the real meaning of Info_3 would be "tell me what you know about
> the object whose name is this-or-that", using perhaps multiple
> dictionaries (or should I say "caches"?) or complicating this idea in
> any other way you like.

Wouldn't the following lookup function handle the situation?

    function Lookup (Table  : Dictionaries.Map;
                     Object : T'Class) return Boolean is
    begin
       return Table.Contains (Object'Unchecked_Access);
    end Lookup;

Object denotes an object, then, so no nulls. Therefore, passing
the result of 'Unchecked_Access to function "Contains" should
be safe in the sense that Contains always gets a meaningful
access value to be used as a key.

The effect is that there still wouldn't be any parameters of an
anonymous access-to-object type at the level of T's definition.